Process and product for forming color images from complete dyes



Dec. 18, 1956 H. G. ROGERS 2,77

PROCESS AND PRODUCT FOR FORMING coma IMAGES FROM COMPLETE DYES Filed May 28, 1953' l2 {Layer Coni'uining Dye |4\ and/or Developer f cn+in.r if fl hofoscnsifivc Layer l5 Print-Receiving Layer 1 FIG l 2| Suppori 22 Conl'oining Dye 23 Lcyu Coniaining Developer 24 Layer FIG. 2

Supporl aIAF Phoioscnsifivc Laycr Confaining 3 4A? Dy: and/or Davclopcr FIG. 3

rPrinP-Rccciviqq Elcmcni 47 Sirafum Coni'ining Dy:

FIG. 4

ATTORNEYS United States Patent 2,774,668 PROCESS AND PRODUCT r012 roR ING' COLOR INIAGES FROM COMPLETE 'DYES V Howard G rRogers, Weston, Mass, assignori to Polaroid Corporation, Cambridge, Mass, a corporation of Delaware Application May 28, 1953, Serial-No. 358,012 I 8 Claims. (CI. 96-29 invention relates to the art of photography' and more particularly to novel processes forqthe formation of dye images and to film units and photographic products for use with such processes.

Objects of this invention are to provide processes for forming color images from complete dyes' and involving the steps of providing, in a silver halide layer of a; photo-- sensitive element having alatent image therein a solution of a dye and a silver halide developer of a character which has at least one oxidationproduct capable'of at least assisting in preventing dye in the photosensitive element from transferring from said photosetnsitive element and comprising a substance reactable with said dye to provide a reaction product having less mobility ,in the photosensitive element than the dye, developing the latent image with said developer and acting upon dyein-ithe'exposed regions of the photosensitive layer. with. developer which is in oxidized condition whereby to substantially prevent the transfer of dye from the photosensitive ele: ment inproportion to the developmentof silver while providing as a further result of silver development inthe photosensitive layer an imagewise distribution comprising mobile dye and unreacted developer, and transferring, at least part of'said dye from said imagewise distr'ibutionto. a print-receiving element locatedin; superposed relation to the photosensitive element and depositing the transferred dye upon the print-receivingelement and; providing an image-in terms of said dye; and alsoto provide processes such as those described which includethe step of; separating the photosensitive element andtheprint-receiving element by stripping said elements apart-following-the depositionof transferred dye on the print-receiving'element; a Further objects of the invention aretto provide processes 2,774,668 Patented Dec. 18, 1956 "ice receiving element-as well as where the transfer ofjdye is '1. effected, substantially to the exclusion of unreacted developer, to the'print-receiving-element; to provide processes utilizing procedures for keeping developer 'out of the print-receiving element and including the employment in the photosensitive element of a nondifiusing developer of the type having a large molecule whereby the developer substantiallythe same'color characteristics as said dye or a substance having color characteristics of adesired nature v Yetother objects of the invention are to provide photogr-aphicproducts comprising. a photosensitive element having a-fli'quid-permeable portion including a silver halide layer, a print-receiving element positionable in superposed relation to the photosensitive element for receiving a transfer image, a container holding at least a liquid positioned for releasingyitsj liquid betweentwo layersofsaid'product', and photographic processing materials, rendered effective by the'release ofliquid 'firom the container, positioned in the product and including a dye which-is soluble: in said'liquid and when dissolved therein is mobile in said photographic product, and also including i a. silver halide develop-er which is soluble in, said liquid of the character set forthvwherei'n dye in solution in the photosensitive element is trapped' or retained at. least adjacent the exposed regions of a silver halide :layer-of said; element by 'the reaction therewith of an oxidation-productjof a silver halide developerof a character cap-able of providing, upon the reduction of latent silvenhalidepto' silver, a substance which is reactable with saiddyedo provide a substantially immobile reaction product in the. photosensitive element, or wherein said dyexis. trapped or retained in the-photosensitive elementby ther usegof,

a silver halide developer of the typetof bis-benzene-sulr fonyl. hydrazide, that is to say, by a developer Whichhasas one, oxidation product thereof a substance, r'eactable with said dye to providea reaction prodnot" having less mobility in the photosensitive element than dye and which has as a second oxidation product a gas used to' form a barrier of bubbles, in the photosensitive element for assisting in preventinglthe transfer ruye 'frbin the exposed regions of thephotosensitive element;

from unexposed and less than completely exposed regions of *a' photosensitive element are transferred to "aprintemploy means for retaining theldeveloper'in the photovelope'rin the photosensitive "element, as well as to'pr'od-f and ischaracterized .by providing, upon} the development of latent silver halide to silver, at least 0(116 oxidation pr'oductwhich is effective to at least assist. in preventing dye present in exposed regions of the photosensitive layer from transferring to the print-receiving element and which comprises a substance reactable Withsaiddye to provide alreaction, product which isl'ess mobile vin the photographic product than said dye.

"Furtherobjects of the invention are toi'providephotographic products of the character describedihaving a'developer characterized by providing an oxidation product reactable with said dye to'provide as areaction product a substance which is substantially immobile in said photosensitive 'c1ernent,as well'as a developer having asa first oxidation product a substance reac-table with dye to provide a reaction product which is l'ess'mobile in the photo-. sensitive element-than the dye exudes a second oxidation product agas' which'is generated in proportion 'to silver development and provides bubblesinthe photosensitive layerin the form of a barrier at" least able to assist in preventing the transfer of dyefirom exposed regions ofthe photosensitive layer. 1 1 1 Still-:further objects of the 'inventiona're'to provide photographic products of the'character 'set' forth whichsensitive element or for keeping 'theideveloperoutof the print-receiving element and including 'the"incorporation in the photosensitive cler'nentofla developer-having a largermolecule of a size sufiicient to immobilize the "deucts'wh'erein both the developer and the dye are transportable to'the print-receiving elementfand especially "in this latter'rega'rd to products havin'g adeveloperwhich provides an oxidation product reactable with dye toprovide :a""substance having sub'stantially-"thesame color characteristics "as-"the dye; and to provide photographic products such as those described contain a dye mordant or an oxidizing agent in the print-receiving elie mentand also such products wherein the dye is com tained in the print-receiving element.

Yet further objects of the invention are to provide photosensitive elements having a support, at least one liquid-permeable layer on the support, silver halidedistributed in a permeable layer of the element, a dye distributed in a permeable layer of the element and a silver halide developer distributed in a permeable layer of the element and wherein the dye is soluble in liquid and the developer is soluble in liquid and provides upon silver development at least one oxidation product effective so as to at least assist in preventing dye present in exposed regions of the-photosensitive layer from transferring from said element and comprising as said oxidation product a substance'reactable with said dye to form a reaction product less mobile in said element than'said dye; and to provide photosensitive elements of the nature described wherein dye and developer of the kind set forth are contained in the same permeable layer or in individual permeable layers of said element including the permeable layer containing silver halide. f

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which wil be indicated in the claims. a

For a fuller understanding of the nature and objects of the invention, reference should be had to'the following detailed description taken in connection with the accompanying drawing wherein:

' Figure 1 is a diagrammatic side elevation of one em bodiment of a film unit forming the subject of this invention and illustrates a product comprising a photosensitive element, a rupturable container and a print-receiving element;

Fig. 2 is a diagrammatic elevation of another embodiment of a photosensitive element forming the subject of this invention;

Fig. 3 is a diagrammatic elevation of still another embodiment of a photosensitive element forming the subject of this invention; and

Fig. 4 is a diagrammatic elevation of a further embodiment of a print-receiving element usable in carrying out the invention.

In general, the photographic processes and products disclosed herein, as in Patent No. 2,559,643, issued on July 10, 1951, to Edwin H. Land for Photographic Product and Process, are concerned with the treatment of'a latent negative image .in a photosensitive silver halide layer whereby to provide a dye positive image in or on another layer which comprises a print-receiving element.

. Inthe just-mentioned Patent No. 2,559,643, there is disclosed a process adapted to be effected with a negative material in the formof a photosensitive element which includes a photosensitive silver halide layer and which has a conventional photographic coupler, for example a phenol, naphthol, pyrazolone or acetanilide type of coupler, and a silver halide secondary color-forming developer preferably incorporated in some permeable'layer of the element. Para-phenylenediamine and derivatives thereofare classic examples'of such developers Other examples include aminophenol types of developers. A positive dye image of a latent image contained in the emulsion layer of the negative element is provided by spreading an alkaline liquid in contact with and between the photosensitive element and a permeable print-receiving element.

The spread liquid permeates into the negative element and developer dissolved in liquid within the element re}. duces the exposed silver halide of the latent image to metallic silver. 'Portions of the developer, which are oxidized as a result of silverdevelopment, react with the coupler in solution andform a dye image which is..co,-.

extensive with the silver image. The unreacted developer and coupler in the remaining solution provide positive image-forming components which are transferred, by ditfusion, from the photosensitive element to the printreceiving element and form thereon an imagewise distribution of unreacted developer and unreacted coupler which, upon oxidation of the unreacted developer, effect the formation of the desired dye positive. Oxidation" of the unreacted developer to cause coupling may be effected by an oxidizing agent incorporated in the printreceiving element or the coupling may be allowed to take place by aerial oxidation of the developer after formation on the print-receiving element of the imagewise distribution of the unreacted developer and unreacted coupler material.

Other related applications which disclose the formation of dye images by coupling development and in a manner generally similar to that heretofore described are the copending applications of Edwin H. Land, Serial No. 702,039, filed October 8, 1946, now Patent No. 2,661,293, for Photographic Product and Process; Serial No. 94,647, filed May 21, 1949, now Patent No. 2,698,798, for Color Photographic Process and Product; and Serial No. 176,961, filed August 1, 1950 (now abandoned and replaced by application Serial No. 448,441, filed August 9, 1954) for Multicolor One-Step Photographic Process and Photographic Product for Carrying Out the Same; and also the copending application of Howard G. Rogers, Serial No; 358,011, filed May 28, 1953 (now abandoned and replaced by application Serial No. 577,711, filed April 1-2, 1956) for Multicolor Photosensitive Film and Process of Making the Same.

Color development making use of conventional couplers and developers of a secondary color-forming type is subject to certain disadvantages. For example, many conventional lcouplers have different coupling rates. This difference in coupling rates makes it difficult to keep negative image-forming reactions separate in each light-sensitive elemental portion of a photosensitive element utilized in carrying out a one-step multicolor process. Additionally, most dyes formed by coupling, especially so formed magenta and cyan dyes, have objectionable absorption characteristics and hence do not produce as accurate color renditions as desired. Furthermore, dyes formed by ordinary color development are, in general, sensitive to acid, and hence images comprised of these dyes may, in time, fade or change color when subjected to acid gases P esent in the atmosphere.

The present invention is concerned with improvements in procedures and products utilized in the aforementioned applications and patentfor the formation'of dyeimages and especially for the formation of dye images by onestep photographic transfer processing. Accordingly, the invention will be described in :connection with such trans fer processes and products useful for carrying out the same, although, as will appear, the invention is not limited thereto. r The-improvements herein are effected by the employment of complete dyes of a character soluble at least in alkaline solution and by the utilization of procedures and materials wherein dye which is substantially uniformly distributed in a photosensitive silver halide layer having latent image therein will be immobilized or trapped or retained 'in' exposed portions of the photosensitive layer upon'development of the latent image to silver. Asa result of development, there will be formed in the photosensitive layer a silver image and an image in terms of the material trapped or immobilizedin the exposed re-. gions of the photosensitive layer, while dye which is. present in those regions of, the photosensitive layer where no exposure or incomplete exposure and silver development have occurred is free for removal therefrom, as for example by transfer,,at least in alkalinesolution. Silver halide, color developers. which are soluble. inalkaline sour,

tion are utilized with complete dyes in the carrying out of W this invention; By this pr'aetice, use- -isrn ade" of some} product resulting fromthe oxidation of'a 'color developer by the development of a latent image in a silver halide layer to immobilize dye in the exposed and developed regions of the photosensitive layer.

Many dyes of the character with which this invention is; concerned are reactable, as byconpli-ng' or-other-reac tion, with an oxidation product of ac'olor developer-tofprovide a reaction product or substancewhich possessesless mobility in a photosensitive element than the'original dye. Reactions of thisnature-occur-when a para-phenylenediamine typeof color developer-which is employed-in the development ofa silver halide layer is utilized in conjunction with a complete dye. Simi-lar reactions take place with aminophenol type developers.

It: hasbeen discovered, although such a discovery is notaa part of this invention,.thatbis-bnzene-sulfonyl hydrazide is.a good silverhalide .developerof black and whiteimag'es. I have discovered, and utilize my discovery in-this invention, that a-developerofthe bis-benzene. sulfonyl hydrazide-type produces, as one product of oxidation, a substance which willreact with-many of the. .corn-... plete dyes named herein, vas by. a coupling Orotherreaction, to. form a compound or. substance possessing less.

mobility in a photosensitive element than the original dye. Additionally, I have found that a substance ,of thejtype ofbis-benzene-sulfonyl hydrazide, .whenused. in the de-... velopment of a latent image, gives off a gas in the ex-.,.

posed regions of the photosensitive layer as itbecomes oxidized in the development of the latent image to silver.v In. the case of bis-benzene-sulfonyl hydrazide, the ga s is nitrogen. Gas whichisproduced during the .develP..,i mentof a latent image will form bubbles in .the;;ph oto sensitive layer. Where the exposureand development is greatest, bubbles areformedin the greatest concentration. Thesebubbles are utilized to, provide a screen orbarrier for dye in theexposed regions of the photosensitive layer whereby to at least assist in immobilizing such dye by preventing its transfer in solutionthrough theseexposed regions.

The invention-alsointends to make use of dyes which, while reacting with arr-oxidation productof a developer, 7

provide a reaction substance which lacks the desired degree of immobility. For example, the reaction product or substance so formedmay be. only-slightly less soluble than ,the original dye. When bis-benzene-sulfonylhydra zide is. employed as a developer, use may be made. of the. bubbles formed by the gas which is emitted upon the oxif, dation thereof to assist in preventing the transfer of the,

mobile reaction product reacted dye.

In instances where the;,substance produced the re}.v I

action of a completedye with an oxidation productof a conventional colordeveloper lacks the desired immobility, a nondiifusing.developerlis; employed, whichhas a large. molecule whereby .thefdeveloper when. incorporated the'photosensitiye element remains substantially immobile V therein. 4-arnino-3;n-butoxydiethylanilineis an example of nondiifusing col or developerwhi ch has a long chain.

on its molecule. Another example is paraarninophenol to which a long carbon chain has been added. In nondiffusing developers of this type, the longflchairi will-be retained on-the developer molecule upon oxidation of the developer so-that the product remaining after oxidation still retain it immobility, iSincethe complete dye enters .intoa reactionwith this product havingthe long chainon.its; mol ecule,.the substance resultingfrorn the,

reaction will also beretained in the photosensitive element.

Several mechanisms are thus presented .by j which acomplete dye, which-is; at. least soluble in alkaline solotion, rnay be immobilized or retained in exposed regions of a photosensitive element while dye in-unexposed re -t gions -of. the element may be removed in solution, asfor; example :by transfer. By wayof recapitulation,,by one;

mechanism an oxidation product of. the developer reacts with the complete dye to form a substance which isless' mobile in a permeable' lay'erof the photosensitive element:

than the unreacted dye. By a second mechanism a gas given off upon the oxidation of the developer is utilized for-immobilizing dye image components in the exposed i regions of the photosensitiveelement by providing a bar-- rier 'or screen.which-substantially bars their transfera Inthe case of abis-benzene-sulfonyl hydrazide typeof developer, the. immobilizing mechanism by which bubbles are produced is availablef As a modification of the first- .j mentioned mechanism, a nondiifusing developerhaving a molecule sufiicientlylarge so that the developerisurea tained-in the .photosens'itiveelement is utilized for im-.- mobilizing? dye image componentsin the exposed regions ofa photosensitive layer.

Common to these. mechanismsisthe fact: thatthefcolor. developer provides at least one substance upon its .OXldae.

tion in the development of a latent imageto silver which. is .capable, of actingas an agent for immobilizingndyea so as to prevent its transfer from a photosensitive element Itrnay be here, noted that experimental data leads. to the.

belief thatimmobilization, of dye image components in situ with thesilver image developed by the developer is carriedput primarily byoneor more of the mechanisms.

just described and that any hardening of the carrier material of the photosensitive layer by reaction withthedeveloper'or some oxidation product thereof is a negligible factor in-trapping and control of the dye.

The substance, .f0rmed by the reaction of acomplete; dye and an oxidation product of the developer'may possess;

color characteristics which are substantially the same as the unreacted dye or which are ,dif fer ent from the un-;.

As will presently a more, fully appear, it is' possible in'carrying' outa transfer proc$5 :to form,the

transfer image either by the use of transferred dye which; remains in unreacted-condition or by the use of: the

product formed upon the reaction of the transferred dye with an oxidation product of the developer. ofa substance formed by the reaction of an oxidation The color product of the developer and a complete dye becomes immaterial in instances where the complete dye is used for transfer image formation.

Uniquely, a developer of. the bis-benzene-sulfonyl by; drazide type provides an oxidation product which reacts. with a complete dye to provide a substance having suba. stantially the same color characteristicsas the unreacted dye. On the other hand, the reaction productof a dye and an oxidation product of a standard color developer is a substance which, while it may possess the desired.-

immobility, usually has color characteristicsdifferent from the unreacted dye For example, ,1,5 dihydroxy naphthalene-4-azo benzene;

isa magenta dye which is reactable with the oxidation.

product of a developer and which, in unreacted condition is of a colorsuitable for use in-the formation of a sub tractive dye image. When 1,5 dihydroxynaphthalene:

to' the previously pointed out ability of the invention to utilize the unreacted dye or. the reacted dyefor the purposes of image formation, it is possible to employ either, of the types of developers just mentioned.

An advantage in the use of bis-benzene-sulfonyl hydrazide as a developer resides in the fact'that it. is im;

transferred to a print-receiving element becomesjoxidized material if bis-benzene-sulfonyl hydrazide vwhichlhas been.

andreacts with unreacted dye which has also'beentrans ferred sincethe reaction product formed willhave substantially the same color characteristics as the unreacted dye.

Ajlarge number of complete dyes are available for the practice of this invention. Because of the wide choice of classes from which dyes may be selected as compared tothe few available classes of couplers, as well as the ability of the invention to utilize a reacted dye molecule or an unreacted dye molecule, it is possible to form images of dyes having more highly accurate absorption characteristics, as well as images of dyes which are substantially stable. Additionally, in cases where a conventional type of color developer is to be immobilized in the photosensitive element, it is possible to achieve rates of development which are higher than those obtained with the para-phenylenediamine developers by the use of stronger color developers such as ring-substituted paraaminophenols as by one example wherein the ring substitution maybe in the form of carbon chains. Furthermore, it is possible, because of the numerous usable dye classes and almost limitless number of dyes in them, to select dyes to carry out a multicolor process wherein the reaction rates of the different dyes will be similar in instances which utilize the reaction of an oxidation product of the developer and a complete dye for the purposes of immobilization.

Among the classes from which suitable dyes are available, mention may be made of the monoazo, disazo, triphenyl methane, xanthene, thiazine and anthraquinone dyes. The field of dye materials is further extended by the employment of dye substances of the type which react with oxidized developer and which, in unreacted form, may be colorless in a particular environment, for example an acid environment, but upon change in the environment, for example to an alkaline environment, take on a color change. Dye substances of this type include indicator dyes, leuco dyes and carbinols of basic dyes.

Complete dyes of the character with which this invention is concerned are employable in a photosensitive element in the same manner as the conventional couplers previously mentioned, i. e., they are preferably incorporated in a permeable layer or stratum of the photosensitive element which may or may not contain other materials used in the photographic process, as for example silver halide and/ or the developer. Dyes of the characteristics described and/or their reaction products should also be stable to light and to photographic solutions.

Dyes which are particularly suited for reaction with an oxidation product of a color developer, including bisbenzene-sulfonyl hydrazide, are found in those dyeshaving an open position on a ring, which position is para to a hydroxyl or an amino group, or those dyes having a reactive methylene group. Many suitable dyes coming within this classification are found among the azo, pyrazolone and triphenyl methane dyes, specific examples of which comprise the following waterand alkali-soluble dyes such as Fast Crimson 6BL (C. I. 57) for magneta; Fast Wool Yellow (C- I. 636) for yellow; Alphazorine 2G (C. I. 712) and Pontacyl Green SX Extra (C. I. 737) for cyan; and Polychrome Blue-Black (C. I. 201) and Rayon Black GSP (which is commercially available from E. I. du Pont de Nemours & Company, Inc., Organic Chemicals Department) for black; as well as water-insoluble but alkali-soluble dyes, such as 1,5 dihydroxy naphthalene-4-azo benzene, for magenta; and Benzene Az'o Resorcinol (C. I. 23) for yellow.

The substance formed by the reaction of a complete d'yeofthe character described with the oxidation product of a standard type of color developer will usually possess color characteristics which are undesirably different from thoseofthe unreacted dye as, for example, the grayish substance formed when the magenta dye, 1,5- dihydroxy naphthalene-4-azobenzene, is reacted with the oxidation product of a para-phenylenediamine type of developer.

It thereforelbeconies necessary to'utilize the unreacted dye molecule for image formation in transfer processing under circumstances wherein a reaction product of a color developer and a dye possesses an undesired color. However, it should be recognized that it is possible to use the reaction product for transfer image formation in instances where the oxidized developer reacts with the dye to give a reaction product which possesses a desired color, although such color may be different from that of the unreacted dye molecule.

Use of the unreacted dye molecule for image formation is made possible, when employing a para-phcnylenediamine or other standard type of color developer, by preventing the reaction, on the print-receiving element, of dye and developer which have been transferred thereto. In this regard, a number of varied practices are available.

By one practice for accomplishing this purpose, there is incorporated in the photosensitive element a developer which possesses a very low solubility in alkali but has good solubility in a high-boiling-point organic solvent. An example of such a developer is 4-amino-di-n-butylaniline. Procedures for carrying out this practice are known to the art and are set forth in Patent No. 2,478,400, as well as in the previously mentioned application Serial No. 176,961. Due to the fact that the developer is of low solubility in alkaline solution, its mobility will be substantially restricted to the negative or photosensitive element.

Briefly stated, practices for incorporating a developer which is difficultlysoluble in alkali in a photosensitive layer are carried out by dissolving the free base of a standard developer in a high-boiling-point solvent such as tricresyl phosphate. The solution thus formed is then emulsified in a dilute gelatin solution containing an emulsifying agent, as for example alkyl lauryl sulfate, and an appropriate amount of the emulsified product is added to a suitable quantity of a silver halide emulsion and is thoroughly mixed therewith. This procedure is also available for incorporating a dye in a silver halide emulsion which, along with the free base of the developer, may bedissolved in the aforementioned high-boiling-point solvent. However, since the dye is also soluble in alkali, it may be transferred in-alkaline solution from the photosensitive element.

Alternatively, a relatively immobile or nondiffusing color developer, of the character previously mentioned, may be incorporated in the negative element as, for example, a developer having a long chain on its molecule such as 4-amino-B-n-butoxydiethylaniline. alternative, the print-receiving element may include, as an image-receptive material, a plastic layer which is of a character displaying a greater aflinity for dye than for developer or a preference for the penetration thereof by the dye overits penetration by developer. As an example of {a receiving sheet material and a dye of these characteristics, mention may'be' made of partially, hydrolyzed polyvinyl acetate and the previously mentioned magenta dye, 1,5-dihydroxy naphthalene-4-azo benzene.

As a' still further means for controlling reaction of the dye in the print-receiving element, a strong reducing agent such as hydroquinone may be incorporated in the positive print-receiving element to prevent oxidation of any transferred developer and consequent coupling reaction.

These and similar practices. are useful individually or in various combinations for the purpose of preventing the reaction of a transferred dye moleculewith developer.

A further understanding of the invention will be gained from a consideration of products useful for carrying it into effect. In this regard, there is schematically shown in Fig. 1 a' film unit making use of a negative sheet material or'photosensitive-element 10 comprising a support 11 of paper or film base material upon which there is mounted, in the order named, a layer 12 comprising a silver halide developer and a dye which is reactable with the oxidation product of the developer and a conventional As a further photosensitive layer 14 of "silver halide. The film unit of Fig l als'o'empl-oys; a-positive-sheet material or-print receiving-element- -15 comprising an image-receiving layer of opaque or transparent material which is Iiquidpermeable and dyeable-from alkaline-solutions and which has beenillustrated for purposes a of simplicity-as comprising a=s ingle sheet, for example, paper. However,; theposi' tive element 15 may'com'pr-ise a-support upon' whichiat" least-one liquid-permeable and dyeable layer is mounted. As shown inFig; 1, the photosensitive-element -and the print-receivingelement 15, for the purpose'of positive 'image formation, are adapted to be placed in super posed-relation and; arearranged so that the photosensitive: layer or stratum-14is$next to-the print-receiving-element- 15. V

Also, in the filmunit of Fig. 1 a rupturable container 16, adapted to carryan alkaline solution or liquid composi tion,-is shownaspositioned transversely of and adhered to the print-receivingelement 15.- Ifdesired-, the container IGmay-beadhered to the photosensitive layer. Container 16'is of a -length approximating the Width of the film unit and is' constructed to carry sufli'cient liquid to effeet'nega tive -imageformationin an exposed-image-area Of' thephotosensitive-layer 14 and positive image formation in the corresponding: image area ofthe print-receiving 'ele--- ment 15.- In use, the container 16 is adapted to be posi tioned between the print-receiving element and the photo sensitiveelement so that it will lie adjacentthe edgesof the corresponding image-areas of these elements whichare to be processed'by the liquid .cont ents ofthe container. When-the film unit is of'the-roll' film-;type', a--plurality of cont airiers are employed, one for each correspondingpainoisuccessive image areas in the photosensitive-and-printreceiving elements. Details of such containers may befound-in Patent No.- 2,634,886, issued-April 14, 1953', to Edwin H. Land for Collapsible Fluid Containers? 'In one embodiment, the layer-l2 'comprises -=a-liquidpermeablecarrier rnaterial in which is incorporated a dyeof the character with which this invention is concerned and 1 preferably'a silver halide developer.- The carrier material with the dye and/or developer therein is coatedonto-thesupport -11-to a thickness ofabout @0001 or-.0002 inch By another embodiment, the layer 12 may be-forrned of dye and developer dissolved in avolat'ile solventor solvent mixture which iscoated directly onto the support 11. The; thickness of the layerlZ when-formedinthelastdesci'ibed manner will; ofcourse, be infinitesimal: In any event-,' the; layer 12 is penetrable'by the liquid processing composition-'- employed so that dye-and/or developer containedthere in "maybe placed" in solution? As will presently be pointed out, it is-possibl e in this embodiment of the invention to locateqthe developeflin the photosensitive layer 14 and; in -certain-instances,1 in

solution in th'e'liquid in the container l6f" Also in embodiment, the dye distributedin-thelayer'12"'is;prefer ably one of the water-insoluble but alkali -solubledy" heretofore mentioned. A- suitable carrier material-when layer 12 comprises carrier in which dyeand developer are distributed is'-onei which will swell in hydroxide or alka1i'ne-liquids-sufliciently to release dye and" developer containedtherein. Examples of carriers comprise gelatin, zein; polym'ethev 1 crylic; acid, shellac -'and-cellulose acetate hydrogen phthal ate,- of which. the latter may be n'amedfas preferredffor".

most general purposes. H

Where layer 12 comprises a carrier material in which;

dye and developer are distributed,"one example of 'a com-[ position for forming the layer is as follows:

1 gram LS dihydroxy naphthalene-4-azo benzene 1 gram 4-amino-3-n-butoxydiethylaniline 4 grams cellulose acetate hydrogen phthalate 80 cc. acetone 20 cc. methanol 1 cc; ethyl Cellosolve In preparing this composition, the dye, developerand...

cellulose acetate 1 hydrogen 'phthalate (the carrier ;'-material) "are mixed together and dissolved in the solvent mix-;

ture providedby the-acetone, methanol and ethyl 'Cell'or' product of-a color "undesired for transfer image formation 10 sothat-the dye-in unreacted condition is intended to be employedto providethetransfer image. As maybe noted the developer in the foregoing-composition is of the-nondiflusing type so that it is substantially kept out of the print-receiving element.- Additionally, a receiving- 15 sheet material suchas partially hydrolyzed polyvinyl acetate maybe usedin the print-receiving element; Other practices such as those of the nature heretofore described are available-for controlling developer transfer in instances the dye is of an undesired color.

When the layer; 12'; is provided from a solution of dye and :developer in a volatile'solvent, one example of a suitablecompositionfor forming the layer isas follows: 1 gram 1,5 dihydroxy.naphthalenel-azo benzene H v 4 grams bis-benzene-sulfonyl hydrazide 100 cc. acetone The just-described composition is prepared by mixing-the dye and developertogether and 'dissolvingthe mixture in tuted for theparticular magentadye of the foregoing formulas.v I

The-photosensiti vesilver:halide layers used herein are provided-by.silVenhalideemulsions of conventional charactenwhich-are coated-onto thelayer 12 after thelatter 40 has dried. The particular sensitivityrange ofeach photosensitive "layensuch as the-layer 12,- will be'chosen to meet the particular requirement of use to which the photosensitive "element will be put. These emulsions are conventionally coatedj onto the layer 14or otherwise applied thereto ma thickness of from about .0002 to .0005 inch.

- As heretofore-mentioned, the image-receiving material of the positive element l5lincludes any material dyeable fromalkali'neliquid- The positive element 15 may,-as shown, comprises asingle sheet of permeable material or it may comprise a support which carries-a layer or a stratum of: a-.permeable-= image-receiving materialo An example of suchisimbibition paper or barytatpaper or 1 conventional film base material upon which a permeable stratum is coated.- As a further example, the printreceiving element may comprise a paper support sub- -coatedwith w substantially water-impermeable material and; dyeable material coated: over the subcoat. Image-receiving materials of a dyeable nature, in a'ddi tionato those already named, include regeneratedc'ellulose; polyvinyl alcohol; partially hydrolyzed polyvinyl acetate; sodium 'alginate; cellulose ethers, such as methyl compatible; ferred image-receiving material for use with water-soluble 70 dyes, especially with water-soluble dyes having sulfonate groupsbnthe dye-molecule. For water-insoluble dyes,

a preferred image-receiving material is partially hydrolyze'd polyvinyl acetate.

The liquidi processing composition employed 7 in carrywhere the reaction-product of the oxidized developer and such asacellulose ester, i."e., cellulose nitrate, cellulose acetate and th'elike, and having a stratum of a permeable cellulose or other cellulose derivatives such as sodium carb'oxymethyl'celluloseor hydroxyethyl cellulose; papers; 1

proteins, such' as glue; carboxydrates, such as gums andstarch; and-mixtures: of such materials where they are Polyvinyl alcohol may be named as a pre-'l line liquid-of suflicient alkalinity to permit the developer to perform its developing function and, in certain .in-- stances, may also have the developer dissolved therein. A viscosity-increasing compound constituting a film-forming material of the type which, when spread over a waterabsorbent base, will form a relatively firm, dimensionally stable film, is preferably included in the liquid processing composition to assist in carrying out the uniform spreading of the composition between the layers of the film unit. A suitable film-forming material is a high molecular weight polymer as, for example, a polymeric, watersoluble ether, inert to an alkaline solution, suchashydroxyethyl cellulose or sodium carboxymethyl-cellulose. Liquid processing compositions of this natureare described in the previously mentioned applications and in Patent No. 2,559,643. A suitable liquid processing composition comprises a mixture of grams of sodium carboxymethyl cellulose, 3 grams of-sodium hydroxide and 100 cc. of water. It is here pointed out that while sodium hydroxide is in general the preferred alkali used in the processing liquid, other alkaline materials may be employed, for example potassium or lithium hydroxide, sodium or potassium carbonate and diethylamine.

The incorporation of an oxidizing agent in the printreceiving element for the purpose of oxidizing unreacted developer permeated therein is disclosed in certain of the previously mentioned applications and in Patent No. 2,559,643. While the present invention will generally be practiced without the use of an oxidizing agent, it may be desirable in certain instances to utilize one. For example, it may be preferred to form a transfer image of the reaction product of the complete dyeand the oxidation product of a conventional color developer in instances where the reaction product has a suitable color. In such a case, or in instances where deepening of hue of the transfer image is desired, such as for black, it would be desirable to include an oxidizing, agentinthe print-receiving element for the purpose of speeding up positive image formation.

As specific examples of suitable oxidizing agents, mention may be made of peroxy compounds such as sodium or potassium perborate, certain dichromates such as ammonium dichromate, and compounds having polyvalent metallic elements in higher valent form such as copper, antimony, uranium, manganese, iron and cerium, wherein the metallic element is in higher valent form. Examples of these last-mentioned agents are cupric salts such as cupric sulfate. Another suitable oxidizing agent is benzoyl peroxide.

To build up greater density of image dye in the positive element, it may be preferable to have aneflicient dyeprecipitating mechanism included in the image-receiving sheet material. Consequently, it is desirable to have a mordant included in the image-receiving sheet, as well as utilizing a print-receiving element having a layer or stratumrwhichhas an affinity for dye, suchas a suitable plastic stratum. 'For this purpose, the print-receiving.

element itself may be formed of a conventional dyetransfer paper which contains a mordant. A suitable dye-transfer paperlis commercially available 'from Eastman Kodak Company under the name of Dye Transfer Double Weight F. As other examples, a print-receiving element may be provided with a gelatin layer containing amordant such as nickelous sulfate or aluminum sulfate. Such a material may be used as the image-receiving stratum of the print-receiving element and is' easily coated upon a support for the element. The use of a mordant in the print-receiving element is disclosed in the 'aforesaid Patent No. 2,559,643.

.As another practice for providing a dye-precipitating mechanism in the print-receiving element, dyes may .be chosen which form lakes with metal salts. Dyes of this character and metal salts usable for thispurpose are well known to the art. Where procedure of'this type is utilized, metal salts such as chromium and/or barium duced to silver and at least one oxidation product of salts are distributed throughout a permeable stratum of the print-receiving element in which the transfer image is provided. a 1

In all products employed in the practice of the invention, it is preferable to expose the negative material or photosensitive element 10 from the emulsion side. It is therefore desirable to hold the photosensitive element 10 and positive sheet material 15 together at one end thereof, by fastening means, not shown .but comprising hinges, staples, or the'like, in such manner that the photosensi-g tive element 10 and the positive element 15 may be spread apart from their positions illustrated in Fig. 1. When the'film unit is of the roll film type, the photosensitive element 10 and the positive sheet 15 are wound into;

separaterolls and the free ends of said rolls areconnected together, in the manner described.

A camera apparatus suitable for processing roll film ofthe type just mentioned is provided .by the Polaroid Land Camera Model or similar camera structure, such for example as the camera forming the subject matter of Patent No. 2,435,717, issued February 10, 1948, to Edwin H. Land forDeveloping Camera Utilizing a Film, Another Sheet Material, and a Fluid Processing Agent; 7

Camera apparatus of this character permits successive exposure of individual frames of the photosensitive element 10 from the emulsion side thereof, as well as individual processing of an exposed frame by bringing the exposed portion of the photosensitive element 10 is superposed relation with a portion of the print-receiving element 15 while drawing theseportions of the film assembly between a pair of pressure rolls which rupture the container associated therewith and spread processing liquid between and in contact with the photosensitive element and the corresponding registered area of the printreceiving element.

Assuming that the film unit of Fig. 1 utilizes a layer 12 containing a magenta dye and a developer in accord ance with one of the preceding formulas, the process-' ing of -,the-unit for transfer image formation, following the'exposure of the photosensitive element 10 to a desired subject, proceeds, by rupturing container 16 and'spread ing the alkaline liquid. processing composition between the photosensitive element and the print-receiving element. a

The spread processing liquid migrates into the photo'-' sensitivelayer 14 and the layer'12. During permeation intothe layer 12, unreacted dye and unreacted developer contained in this layer are dissolved in the processing liquid and are transported in solutioninto the photosensitive layer 14.

dized as a function of the amount of silver haliderethedevel oper reacts with the dye adjacent the developing silver grains to form a reaction product. 'As previously noted the product of the reaction of dye and the oxidationcproduct of the developer is at least less mobile in the, photosensitive element 10 than the dye itself. 7

For generalpurposes in cases where the developer isbis-benzene-sulfonyl hydrazide or where the developer is kept-.out of the print-receiving element, an excess of developer may be'utilized in the photographic product. However, in instances where an oxidation product of the developenreactswith dye to provide a substancepf desired ,color,,developer is employed in a quantity controlled to avoid highlight stain in the transfer image' By this control, developer is utilized in a unit area of the layer, adapted .to have the developer incorporated therein, in a quantity just sufiicientpto be completely oxidized by a fully developable orcompletely-exposed silver halide portion of similar unit area. t v

In general, dye present in a dye-containing layer ina' unit area thereof similar to that described is'pr'eferably of a quantity just suflicient to be entirely reacted by that amount of developer which is oxidized by the development of a completely exposed unit area of the-photo" sensitive layer. This procedure is likewise for the purpose of avoidingwhighlight.stain in the transfer image. However, if the. dye employed in the photosensitive element has a sufficientlylow solubility: rate, it is possible to use dyein excess ofthat .justspecified.

As intimated. in the foregoing, processing of the-nature described forms a.substantiallyuniformdistribution of dye and developerin the photosensitive layer 14 so that,-

upon development of .silver, dye in the. area of the highlights .of the negative image issubstantially exhausted by reason of. its reaction with an oxidation productofthe developer to;provide a product which is at least less mobile in, the negative sheet material thanthe dye-itself. When the developer employed is bis-benzenesulfonyl hydrazide, thegaseous oxidation product thereof provides, an additional trapping or; immobilizing mechanism by forming a barrierjof bubbles adjacent the. developed regions .of,:the.-photosensitive layer whereby :to

development out :of the photosensitive element.

As a further result .of processing, inplaces in thenegative -material where unexposed ,silver halide grains are present or in places .Whereexposure-and subsequent development is less than complete, unoxidized or unreacted developer and dye are in an ,imagewiseadistribution. proportional to silver.- development, Dye. and-developer -2O assist inpreventing transfenof the reaction product of present in this image wise distribution. are both trans-.

portable, at least in part, by imbibition to the-printreceiving element. However, the 'unreacted developer may .be prevented from entering the-print-receiving elementby utilization of one of the precautions ,or prac-. tices previously described, such as, the use of a.non.---

ethylaniline, or by the employment of-a developer ,which'.

diffusing developer, for example ,4-amino-3i-n-butoxydibenzene-sulfonyl hydrazide=-developer will take place slowly: and solely from aerial -oxidationi- Consequently,- the print-receiving element and-thephotosensitive eler them may be stripped apart at leastat-a time when oxidationof thetransferred developer isjust being initiated.-

Under these circumstances and because of thestripping of the print-receivingelement from the photosensitive element, gas generated by the developer upon its oxidation will. besubstantially free to' escape into the surrounding atmosphere.- As a result,.the print-receiving element will be substantially freeof thebubbles which were used for trapping purposes in the negative-sheetmaterial or photosensitive. elementnlfis I 1 Where the developer is a standard color developer of the. usual type such as para-phenylenediamine, an oxidizing agent such as disclosed in said Patent No.

2,559,643 is preferably included in the, print-receivingelement in instances Where the reaction which takesplacebetween the oxidation product of the standard color,

developer and the transferred dye provides a substance having the desired color characteristics. As pointed out,

the use of an oxidizing agent, while not necessary, considerably speeds up reactions of this sort. I

In the film unit of Fig. l, a construction beendetailed wherein the developer and the complete dye are located in a stratum in back of the photosensitive stratum or between the photosensitive stratumrand the'support of;

the photosensitive element 10. This construction is generally preferred in carrying out a transfer process since it facilitates control ofthe'reactantsto the end of achieving substantially complete trappingor immobilization of dye-and developer utilized in providing the negative image in the. photosensitive element with consequent avoidance Offihighlight colorinthe positive; t

However, the preferred construction is subject to con T siderable variation. Fol-example, a layer or stratum conisdifficu1-tly soluble in alkali, such; as 4-arnino-di-nel butylaniline. In all instances, the inventionintends to.

transfer at least-part of thedye toythe-prinbreceiving element to provide an image in terms of, unreacted. dye which is the ,reverse image. of the latent image in the photosensitive element.

Following the jformation onthe print-receiving ele-i mer t of a reverse image of thelatent image, the photosensitive element and-the I print-receiving;element are separated, as by beingstrippedapart. .,In instances, where the developer-is retained in the photosensitive I element 10 and/ or is kept out of the"print-receiving elee ment :15, the reverse imagev 0n element 15 will comprise An advantage -of this pro-- cedure resides inthe simplification of processing andfilm unitconstructionby doing away withvthe need ffOI'F'aHZ.

dye in unreacted condition.

oxidation agent ;in the print-receiving element;-

This simplification isenhanced when a devel the bis-benzene-sulfonyl, hydrazide type is employed, since such a developer need not bekept out of the print-j In instances where unoxidiZed.;bis-,.

receiving element. benZene-sulfonyl hydrazide is; transferred 7, to i the, printreceiving. element, any subsequent oxidation thei eofsis;

immaterial because of .the fact that the reaction between dye, and anoxidation produet of the bis-benzene-sulfonyl hydrazide will provide a substance having substantially the same color characteristicsas the dye itself. i

As heretofore noted, bis-benzene sulfonyl hydrazide upon its oxidation-gives off a gas. QWhen bis-,benzene-z sulfonyl hydrazide in-unoxidized conditionis transferred?" to-the print-receiving element from the imagewiseEdisa tribution of developer anddye in-the ph0tOS6I1SltlV 6 6le:

ment, it will eventually become oxidized from aerial.

tainingthe developer and/or unr'eacted dye may be lo- Also, the

cated in .front of the photosensitive layer. developer-and the unreacted 'dye may be incorporated in individual strata of the photosensitive element, including the incorporation of 'oneofthe se photographic materials in the photosensitive layeritself: Furthermore in' cer-' tain instances it is possibletoi-ornit the developer and/ or dye from the photosensitive element and to'include either or both intlie alkaline liquid used for processing pur-- poses. Also,:the dye-may be distributed in a stratum lo cated on the-side of the print-receiving element which" is adapted to face the photosensitive element in instances where a nondiffusing type-of developer is incorporated in the photosensitive element; a

It has been previously pointed out that-the photosensitive element 10 is designed preferably for use with a waterinsoluble but alkali+soluble dye. In general; many dyes Willexerta desensitizing action on a silver halide emulsion if they become intimately mixed therewithpas for exam-- ple by being imbibed into the emulsion from a solution of the dye'.' Desensitization may be of chemical or physical character whereby the sensitivity of the silver halide is.

lowered. Also desensitization may be of an optical nature,'th'at is to say",*dye whichisjintimatelymixed with a silver-halide ernulsionwillabsorbfl actinic light intended] for-the exposure'o fthe emulsion;

. In foiming the photosensitive element 10, the silver halide emulsionprovidingfthe layer;14 is'coated onto the flayer 12;.afterth e latter dried ltis possible for water or moisture in the wetemulsion. to penetrate into.

the layer '12 although the carrier material for layerill is difiicultly penetrable by water but is readily penetrated by alkaline solutions. If dye incorporated in the layer 12 is of a water-soluble nature, there is some likelihood of its entering into solution inwaterfrom the wet emulsion with subsequent migration into thephotosensitive layer. In the photosensitive element 10, this possibility is avoided by utilizing awater-insoluble but all;ali-solubledye, for r example, a dye such as the previously mentioned 1,5 dihydroxy naphthalene-4-azo benzene.

In instances where a dye which is soluble in water, as well as in alkali, is employed, a somewhat different type of photosensitive element is utilized. Such an element is shown in Fig. 2 and comprises a support 21 upon which is coated a layer 22 adapted to contain a watersoluble dye which is incorporated in a carrier material of the character previously described, for example, cellulose acetate hydrogen phthalate or gelatin. Coated upon the dye layer 22 is a barrier layer 23, comprising a carrier, such as cellulose'acetate hydrogen phthalate, in which the developer is incorporated.

One composition suitable for forming a layer 22 comprises:

1 gram Fast Crimson 6BL (water-soluble dye) 2 grams gelatin 100 cc. water An example of a composition suitable for providing the barrier layer 23 comprises:

4 grams cellulose acetate hydrogen phthalate 4 grams bis-benzene-sulfonyl hydrazide 80 cc. acetone 20 cc. methanol 1 cc. ethyl Cellosolve Afterformation and drying of the layer 22, the layer 23 is applied thereon and, following the drying of the layer 23, the silver halide photosensitive layer 24 is coated on the layer 23. While water from the wet silver halide emulsion forming the photosensitive layer 24 may penetrate into the barrier layer 23, the barrier layer 23 may be made sufiiciently thick so as to substantially prevent penetration of moisture from the wet emulsion of layer 24 into the layer 22 which contains the water-soluble dye. The photosensitive element 20 of Fig. 2 is susceptible to modification without change in its structural arrangement of layers. For example, the developer may be omitted from the layer 23 and included in the layer 22 or even in the photosensitive layer 24. p

In instances where the reaction product of the dye and the oxidized developer are of an undesired color, transfer of the unreacted developer to the print-receiving element may be controlled or restrained by any of the procedures heretofore noted. For example, an appropriate amount of a nondiffusing developer, such as 4-amino-3-n-butoxydiethylaniline may be used in the last-disclosed formula, or any of the other practices described are available.

The invention includes Within its concept the incorporation of both the dye and the developer in layer 22 of the photosensitive element 20. In this instance, the barrier layer 23 will'consist substantially only of the material which forms it.

The photosensitive element 20 is formed in a manner similar to the photosensitive element and utilizes substantially similar materials for the purposes of construction. Likewise, the photosensitive element 20 is adapted to be used with a print-receiving element of the nature disclosed in Fig. l and in a similar manner for providing, in the print-receiving element, a dye image which is the reverse image of a latent silver halide image formed in the photosensitive element upon exposure thereof.

It has been further mentioned as an object of this inr 1% to the art for incorporating a coupler and a developer therein.

A developer such as bis-benzene-sulfonyl hydrazide may be incorporated in a silver halide emulsion by dis solving 1 gram of bis-benzene-sulfonyl hydrazide in 30 cc. of acetone and stirring the solution thus formed into 70cc. of an appropriate silver halide emulsion.

Where the developer employed is of the type which provides a substance of an undesired color upon the reaction of its oxidation product with dye, the invention may be carried out with a nondiffusing developer or by utilization of other practices of the character heretofore mentioned for controlling the transfer of the developer to the receiving sheet. In this regard, one nondiffusing developer for use with the photosensitive element 30 of Fig. 3 is the previously mentioned nondiffusing developer, 4-amino-3-n-butoxydiethylaniline. A composition comprising silver halide and 4-amino-3-n-butoxydiethylaniline of a nature suitable for providing the photosensitive layer 34 may be formed by dissolving the hydrochloride of the developer in water to which an approximately equal amount of phosphoric acid has been added. The solution thus formed is added directly to the silver halide emulsion and the mixture is spread upon the support 31 to provide the photosensitive layer 34.

As previously set forth, there is a tendency among many dyes to efiect emulsion desensitization when the dye is incorporated in a silver halide emulsion. Preferably, the invention utilizes a dye of a nature which exerts a minimum chemical and/or physical desensitizing action on a silver halide emulsion. Preferably, also, the dye employed is of a water-insoluble nature whereby to limit its intimate m'mture with a silver halide emulsion to the :endof-avoiding possible optical desensitization. An exhalide grains whereby to lower the covering power of the."

sion. These dye-containing particles may be formed by procedures similar to those taught in U. S. Patent No. 2,618,553.. In place of hardened gelatin, the dye may be incorporated in particles of a material which is difii-' cultly penetrable by water but is readily penetrated by alkaline solutions such, for example, as the cellulose acetate hydrogen phthalate, already mentioned, or simi lar materials. Colored dye materials which are incorporated in a photosensitive layer preferably have a particle size which is greater than the particle size of the silver dye to 'permit photographic exposure of the photosensitive layer to its full thickness.

Mention has been made of compounds in the nature of dyes which are substantially colorless in a particular environrnent butbecome colored when this environment is changed. Such compounds include indicator dyes, leuco dyes and carbinols-of basic dyes. Dye substances of this nature should possess the properties heretofore enumerated as requisites for carrying out the purposes of this -invention and, in addition, should preferably be colorless or yellow or slightly so in aneutral or acid environment. For A example, indicator dyes such as '2,5-dinitrophenol, quinaldine red and quinoline blue have, respectively, a yellow, a red and a blue color at a relatively high pH but are substantially colorless in a neutral or acid environ- Practices for incorporating dye and a developer in a silver halide emulsion are similar to those well understood menti. 7

Such dye substances as those capable of assuming a color change are especially adapted for use with a photosensitive element having a layer of silver halide in which the dye and the developer are incorporated as, for example, the photosensitive element 30 of Fig. 3. Since dye substances of this nature are utilized in a photosensitive element in their colorless form, it is possible to increase the concentration of the dye substances in the element without having any effect upon the satisfactory exposure of the photosensitive layer. Preferably, the dye of this nature is colorless at a pH of about 7. To provide an acid environment in the photosensitive layer, a suitable acid such asan appropriate amount of phosphoric acid may be added to the photosensitive emulsion. Alkali contained in the processing liquid will, in general, supply the alkaline environment needed for creating the desired color change in the dye substance. If dye substances of the nature. under discussion exert a desensitizing effect upon the silver halide, practices such as those described may be utilized to restrain desensitization.

When a dye substance which is colorless in a neutral or acid environment is utilized in a photosensitive element such as the element 30, the portions of said sub-. stance which are employed to provide the positive image are transferred. to the print-receiving element in unreacted form. Under these conditions,it is also desirable to utilize one of the practices, previously pointed out for restraining reaction of oxidized developer on the printreceiving element with transferred dye. The processing 7 of the photosensitive element 30 is carried out in a manner similar to that heretofore detailed. In the case of some dye substances which change color according to their environment, it may be desirable to incorporate alkali, for example sodium carbonate, in the print-receiving element. Also, in the case of leuco dyes and carbinols of basic dyes, it may also be desirable to include an oxidizing agent in the print-receiving element for the purpose of speeding up the color change. Both of the lattermentioned practices are included within the scope of the present invention.

The photosensitive element 30 is especially adapted for use with the embodiment of the invention wherein a photosensitive element has a nonditfusing developer incorporated in the photosensitive layer thereof and such an element is utilized with a print-receiving element 45 which carries a stratum 47 of dye coated on the side thereof which is adapted to face the photosensitive element when processed. A dye stratum 47 is provided by incorporating the dye in a volatile solvent, for example 1 gram of dye in 100 cc, of acetone, and by coating the solution onto the surface of the print-receiving element '45. Print-receiving element 45 comprises any of the embodiments thereof heretofore specifically discussed. As another practice, the dye utilized may be incorporated in a carrier material, such as one of those already described, for coating in a thin layer upon th print-receiving element. In this embodiment, the photosensitive layer is prepared in the manner 'described from a composition comprising a silver halide emulsion to which has been added a solution of the hydrochloride of the developer in water and phosphoric acid.

In the embodiment of the invention'utilizing a printreceiving element 45, a dye-precipi tating mechanism is provided by the oxidation product of the nondilfusing developer incorporated in the photosensitive layer. Liquid spread between the photosensitive element and the print-.

sensitive elementin the exposed regions of the photosensi- -tive layer where it is acted on by the oxidation product of the developer and becomes substantially immobilized entrapped in the photosensitive element. Onthe other 18 is the reverse of the latent image formed in the photosensitive element.

In cases where a photosensitive element is employed in which dye is incorporated, it is possible to make two or more transfer prints from the photosensitive element. This may be accomplished by utilizing a dye which is slowly soluble in alkaline solution and by employing a quantity of this dye in the photosensitive element which is in excess of that needed to provide a transfer print. Due to the fact that the dye used in this procedure is in excess of that required to provide atransfer printand because of its slow solubility rate, a quantity of this dye at least sufiicient for a second transfer print remains in the processed photosensitive element. A second transfer print maybe obtained by pressing the photosensitive element against an unused print-receiving element into which has been permeated asolvent for the dye. When sodium hydroxide is the alkali added to the liquid employed for processing the latent image, the dye in the photosensitive element will, in most instances, be converted to its sodium salt when in solution in the liquid. In general, the sodium salts of dyes are water soluble so that water may be employed as the liquid or solvent for effecting the second transfer of dye although, if necessary, an alkaline solution may be utilized. I

Additionally, a photosensitive element such as the element 30 is useful in carrying out practices of this inven tion wherein the dye and/ or the developer are included in theprocessing liquid such, for example, as in a container 16, although as heretofore pointed out it is usually preferable to incorporate both the dye and the developer in the photosensitive element.

Modifications of the film structure, in addition to those already discussed, are included within the scope of the invention. For example, either the photosensitive element 10 or the photosensitive element 20 is useful for carrying out the invention when the developer is omitted from the element and is included in the processing liquid as in the container 16 shown in Fig. l. The photosensitive element 10 is also available for practices wherein the developer is incorporated in the layer 12 thereof and dye is in solution in the processing liquid in container 16. Other modifications of the photosensitive elements are possible. For example, either of the photosensitive elements 10 or 20 may include between the respective bases and the photosensitive layers thereof an additional liquidpermeable layer. 'tributed throughout such an additional layer and dye may be distributed throughout the .layer 12 or 22, or this procedure may be reversed. Also, as has been indicated, both the dye and the developer may be incorporated in the layer 22 of the photosensitive element 20.

I hand, dye which m-ay'migr'ate intdthe photosensitiveelement but is'no'tacted' upon by the oxidation product of the developer is av-ailab le in the usual manner for formation, on the print-receiving element, of a dye image which Theinvention also'contemplates the modification of dyes to the end of improving their characteristics foruse in the processes described herein. For example, a dye has sulfonate groups added theretogSueh groups are solubilizing so that ifa dye is too soluble and transfers too fast, it can be appropriately modified by omitting these solubilizing groups or by adding carbon 'chains of suitable lengths tothe dye molecule.

Furthermore, a dye may be modified in other ways. For'example, if the "dye .does not couple efficiently with f the color developer employed, it may be modified by conden'sation with a phenolor naphthol preferably having a 'chl'oro group or groups para to the OH groupof the phenol and in such a way that there is no conjugation be- "tween the newcoupling function and the original dye, or,

if 't'he' color of the original dye has changed, this change In such event, developer may be'dis- 19 is in a desired direction. As a further illustration it may be noted that it is, in general, most convenient if the dye is insoluble in water but is soluble in alkali. To decrease the solubility of such a dye in water, sulfonate groups thereon may be replaced with carboxy or sulfonamido groups. Generally, replacement of the sulfonate groups in this instance is preferred because omission of the sulfonate groups without replacement may deleteriously affect the stability of the dye.

It is particularly pointed out that practice of the invention is not limited to the use of cyan, magenta or yellow images. For example, dye positive images of a color other than those just mentioned are obtainable when several dyes, rather than a single dye, are employed in the photosensitive layer. The result of such an expedient is to give a positive image different from each of the individual dyes that are utilized for image formation. Thus, it is possible to form black and white dye positive images by the use of suitably colored dyes in appropriate quantities which, when added together, give black.

While the present invention is particularly suited for the formation of colored images, it is to be especially observed that practices herein are also utilizable for the formation of black and white positive images by the use of a mixture of dyes as just described or by the use of a single dye which is black such as, for example, any one of the black dyes heretofore mentioned. Additionally, the use of a black dye or a mixture of dyes which together provide black may be utilized for forming a black component in a multicolor picture.

The present invention finds particular utility in the field of color photography and, in addition to providing for the formation of monochromatic images of a single color, is useful in providing multicolor images. For example, the practices set forth herein may be used to provide the light-sensitive elemental portions in a multicolor photosensitive element of the type set forth in the previously mentioned application Serial No. 176,961 and also in my previously mentioned application Serial No. 358,011. Such multicolor photosensitive elements are processed in the manner described in the just-mentioned applications for providing in one step a multicolor image on a print-receiving element.

Additionally, two or more transparent print-receiving layers, each containing an individual color component image of a multicolor image, may be assembled in superposed and registered relation on a common support in a manner well understood by the art whereby to provide the desired multicolor image.

As another example, the invention is adapted for multicolor work carried out with special film units wherein two or more appropriately sensitized photosensitive elements are associated with a like number of print-receiving elements in a manner similar to that set forth in the copending application of Edwin H. Land, Serial No. 730,661, filed February 25, 1947, now Patent No. 2,647,049, for Photographic Element for Color Photography and a Process of Producing Multicolor Pictures. Also, as shown in the last-mentioned application, a plurality of color component images may be formed in the same print-receiving element by successively bringing the print-receiving element into registered contact with individual negative elements, each of which latter contains a negative latent image representative of a positive color component image to be formed in the print-receiving element.

Furthermore, the invention is useful for copying purposes from separation positives with any of the types of film units described. Of course, when the invention is used in the production of photographic originals, the spectral sensitivity of the diiferent emulsion layers must be suitably chosen. For instance, instead of using a bluesensitive emulsion, a panchromatic or a specially red sensitized emulsion is employed for producing a cyan positive image. positives, this is obviously unnecessary.

However, for copy work from separation Also, as has been intimated, photosensitive elements of this invention are available for color image formation therein, such, for example, as a master negative image; In this regard, a photosensitive element containing a dye and a silver halide developer of the character describedis exposed to a suitable subject, and the photosensitiveelement is then permeated with the usual alkaline liquid.- The result of permeation of the alkaline liquid into the photosensitive element is to develop latent image therein to silver and a colored substance which is in situ with the silver image and is less mobile in the element than dye, this colored substance comprising the reaction product of dye in the photosensitive layer and an oxidation product of the developer.

As the result of development there is also provided in the photosensitive element an imagewise distribution of dye and unreactecl developer in the unexposed regions of the photosensitive element which is removable, as for example by washing, from the element. Following the removal of dye and developer, there remains in the photosensitive layer a silver image and a color image comprising the relatively immobile colored substance in situ with the silver image. The silver image may then be removed by the use of conventional silver bleaches which will not harm the substance providing the colored image, for example a bleach such as a mixture of a sodium or potassium halide and potassium ferricyanide. Prior or subsequent to bleaching, the photosensitive layer may be fixed in conventionalmanner. If the developer, because of its low mobility, is difiicult to wash out of the photosensitive element, it is possible to effect its deactivation by appro priately acidifying it.

While a liquid container 16, which has been illustrated with the film units of this invention, provides a convenient means for spreading a liquid composition between layersof a film unit whereby to permit the processing to be carried out within a camera apparatus, the practices of this invention may be otherwise effected. For example, a photosensitive layer, after exposure in suitable apparatus and While preventing further exposure thereof to actinic light, may be removed from such apparatus and permeated with the liquid processing composition as by coating the composition on the photosensitive layer or otherwise wetting the layer with the composition, following which the permeated layer, still Without exposure to actinic light, is brought into contact with a print-receiving element for image formation in the manner heretofore described.

It is also to be kept in mind that the invention may be successfully practiced Without the use of a film-forming material in the liquid processing reagent. As an illustration, with this latter expedient, a nonviscous processing composition is particularly applicable and may be applied to the negative material by imbibition or coating practices and may be similarly applied to the print-receiving element before the latter and the negative material are brought into superposed relation or contact for carrying out the transfer of positive image-forming components.

Since certain changes may be made in the above prodnets and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A process of forming images in color which comprises absorbing a liquid into a photosensitive element including a photosensitive silver halide layer having a latent image therein and. providing in solution insaid layer a substantially uniform distribution of (l) adye which possesses a coupling function and which is reactable with oxidized portions of a silver halide developer, said dye being mobile in said photosensitive layer when dissolved in said liquid and (2) a silver halide developer capable of providing, upon the development of said latent '21 image to silver, a gas which is generated in the exposed regions of said photosensitive layer and which thereby forms bubbles at least in the photosensitive layer and adjacent said exposed regions thereof, developing said latent image to silver with said developer in said photosensitive layer and immobilizing said dye in exposed regions of said photosensitive layer, said immobilization being effected at least in part by the formation of a barrier comprising bubbles of a gas formed in said photosensitive layer as a result of the oxidation of said developer while providing in said photosensitive layer as a further result of development an imagewise distribution comprising mobile dye and unreacted developer and transferring from said photosensitive layer, by i-mbibition, at least part of said imagewise distribution of mobile dye to a printreceiving element located in superposed relation to said.

photosensitive element to impart to said print-receiving element an image in terms of said mobile dye.

2. The process of forming images in color as defined in claim 1 wherein said print-receiving element and said photosensitive element are separated from superposed relationship at some stage of said process after the imagewise distribution of dye has been transferred from said photosensitive element to said print-receiving element.

3. The process of forming images in color which comprises spreading a liquid in a layer between and in contact with a photosensitive element comprising a photosensitive silver halide layer having a latent image therein and a print-receiving element comprising an image-receiving layer, absorbing said liquid into said photosensitive element including said photosensitive layer and providing in solution in said layer a substantially uniform distribution of (1) a dye which comprises a coupling function and which is reactable with oxidized portions of a silver halide developer, said dye being mobile in said photosensitive element when dissolved in said liquid and (2) a silver halide developer capable of providing upon the development of said latent image to silver at gas which is generated in the exposed regions of said photosensitive layer and which forms bubbles at least in said photosensitive layer and adjacent said exposed regions thereof, developing said latent image to silver with said developer in said photosensitive layer and immobilizing said dye in said exposed regions, said immobilization of dye in exposed regions being effected at least in part by a barrier comprising bubbles formed in said photosensitive layer by said gas produced by said developer upon development of a latent image, providing as a further result of development an imagewise distribution comprising mobile dye and unreacted developer in said photosensiitve layer and transferring from said photosensitive layer by imbibition at least part of said imagewise distribution of dye to a print-receiving element located with respect to said photosensitive element in superposed relation thereto for receiving a deposition of liquid from said photosensitive layer to deposit said dye contained in said imagewise distribution upon said print-receiving element to impart thereto an image in terms of said dye. v

4. A process of forming images in color as defined in claim 1 wherein both the unreacted developer and the dye present in said imagewise distribution in said photosensitive layer are transferred, by imbibition, at least in part to said'print-receiving element.

5. A process of forming imagesin color as defined in claim 1 including the step of mordanting insaid printreceiving element dye which is transferred thereto.

6. A process of forming images incolor which comprises absorbing a liquid into a photosensitiveelement including a photosensitive silver halide layer having a latent image therein and providing in solution in said photosensitive element to -eifect the processing thereof. and when so dissolved beingmobile in said photosensitive layer a substantailly uniform distribution of 1) a dye which comprises a coupling function and which is react able with oxidized portions of a silver halide developer, said dye being mobile in said photosensitive element when dissolved in said liquid and (2) bis-benzene-sulfonyl hydrazide, developing said latent image to silver with said bis-benzene-sulfonyl hydrazide and immobilizing said dye in exposed regions of said photosensitive element said immobilization being cheated at least in part by the formation of a barrier comprising bubbles 'of a gas formed in said photosensitive layer as a result of the oxidation of said his-ben'zene-snltonyl hydrazide while providing as a further result of development an imagewise distribution comprising mobile dye and unreacted bis-benZene-sulfonyl hydrazide and transferring from said photosensitive element, by imbibition, at least part of said imagewise distribution of mobile dye to a print-receiving material located in superposed relation to said photosensitive element to impart thereto an image in terms of said mobile dye.

7. A photographic product comprising a photosensitive element having a liquid permeable portion including a silver halide photosensitive layer, a print-receiving element for receiving a transferred image and a container holding a liquid, said photosensitive element, said printreceiving element, and said container being attached together to permit at least a portion of said print-receiving element and said photosensitive element to be superposed with said container so positioned as to be capable of being ruptured and of releasing its liquid content to at least partially permeate said superposed print-receiving element and photosensitive element including said photosensitive layer, said product having positioned therein (1) a dye which comprises a coupling function and which is reactable with oxidized portions of a silver halide developer, said dye being soluble in said liquid and mobile in said photographic product when in solution in said liquid and (2) a silver halide developer which is also soluble in said liquid and which upon the development of a latent silver halide image to silver provides as an oxidation product a gas which is generated in the exposed regions of said photosensitive layer and forms bubbles at least in said photosensitive layer and adjacent said exposed regions thereof to provide a barrier to at least assist in preventing the transfer of dye from said exposed regions of said photosensitive layer, said developer being bis-benzene-sulfonyl hydrazide, said materials being rendered effective upon the rupture of said container for providing in said photosensitive layer a substantially uniform distribution of said dye and said bis-benzene-sulfonyl hydrazide in solution in said liquid, thereby to develop a latent image in said photosensitive layer and to form said gas and to immobilize said dye in said exposed regions as well as to provide in the photosensitive layer an imagewise distribution comprisnig dye and unreacted bis-benzene-sulfonyl hydrazide, at least said dye in said imagewise distribution being in mobile condition and transportable from said photosensitive element to said print-receiving element for imparting to said printreceiving element a transfer image in terms of said dye.

8. A photosensitive element comprising a support, at least one liquid-permeable layer mounted upon said support, photosensitive silver halide substantiallyuniformly distributed throughout a permeable layer of said element,

drazide substantially uniformly distributed throughout a permeable layer of saidphotosensitive element, said dye and said bis-benzene-sulfonyl hydrazide being soluble in a liquid processing composition permeated into said element. v

References Cited in the file ofthis patent 1 UNITED STATES PATENTS (Other references on following page) I Fischer Jpne 30, 1914.

23 UNITED STATES PATENTS Schinzel Dec. 29, 1942 Knott Apr. 6, 1943 Davey Oct. 12, 1945 Hanson Sept. 21, 1948 Glass et al. Nov. 9, 1943 Jelley et a1. Aug. 9, 1949 Kendall et a1 Feb. 13, 1951 Land July 10, 1951 Broughton et a1 Oct. 21, 1952 FOREIGN PATENTS France Oct. 6, 1931 Great Britain Aug. 9, 1950 

1. A PROCESS OF FORMING IMAGES IN COLOR WHICH COMPRISES ABSORBING A LIQUID INTO A PHOTOSENSITIVE ELEMENT INCLUDING A PHOTOSENSITIVE SILVER HALIDE LAYER HAVING A LATENT IMAGE THEREIN AND PROVIDING IN SOLUTION IN SAID LAYER A SUBSTANTIALLY UNIFORM DISTRIBUTION OF (1) A DYE WHICH POSSESSES A COUPLING FUNCTION AND WHICH IS REACTABLE WITH OXIDIZED PORTIONS OF A SILVER HALIDE DEVELOPER, SAID DYE BEING MOBILE IN SAID PHOTOSENSITIVE LAYER WHEN DISSOLVED IN SAID LIQUID AND (2) A SILVER HALIDE DEVELOPER CAPABLE OF PROVIDING, UPON THE DEVELOPMENT OF SAID LATENT IMAGE TO SILVER, A GAS WHICH IS GENERATED IN THE EXPOSED REGIONS OF SAID PHOTOSENSITIVE LAYER AND WHICH THEREBY FORMS BUBBLES AT LEAST IN THE PHOTOSENSITIVE LAYER WHEN DISADJACENT SAID EXPOSED REGIONS THEREOF, DEVELOPING SAID LATENT IMAGE TO SILVER WITH SAID DEVELOPER IN SAID PHOTOSENSITIVE LAYER AND IMMOBILIZING SAID DYE IN EXPOSED REGIONS OF SAID PHOTOSENSITIVE LAYER, SAID IMMOBILIZATION BEING EFFECTED AT LEAST IN PART BY THE FORMATION OF A BARRIER COMPRISING BUBBLES OF A GAS FORMED IN SAID PHOTOSENSITIVE LAYER AS A RESULT OF THE OXIDATION OF SAID DEVELOPER WHILE PROVIDING IN SAID PHOTOSENSITIVE LAYER AS A FURTHER RESULT OF DEVELOPMENT AN IMAGEWISE DISTRIBUTION COMPRISING MOBILE DYE AND UNREACTED DEVELOPER AND TRANSFERRING FROM SAID PHOTOSENSITIVE LAYER, BY IMBIBITION, AT LEAST PART OF SAID IMAGEWISE DISTRIBUTION OF MOBILE DYE TO A PRINTRECEIVING ELEMENT LOCATED IN SUPERPOSED RELATION TO SAID PHOTOSENSITIVE ELEMENT TO IMPART TO SAID PRINT-RECEIVING ELEMENT AN IMAGE IN TERMS OF SAID MOBILE DYE. 